The findings don’t necessarily alter expectations about the looming threats of climate change. But they underscore how greenhouse gas emissions are changing the face of the Earth. “Because of climate change, human beings are deforming our planet,” said Frederikse.
Satellites measure sea levels by comparing their position in orbit to the distance from the ocean surface. But they use the center of the Earth as their reference point. They wouldn’t necessarily see a change in the volume of the oceans as they grew deeper, the researchers wrote.
The team received support from the Netherlands Organization for Scientific Research, the Australian Research Council and the Australian Research Council Special Research Initiative for Antarctic Gateway Partnership and Discovery Project.
Scientists knew that the seabed contracts under high tides and expands during low tides, so the findings weren’t a surprise, said Don Chambers, a professor in the College of Marine Science at the University of South Florida who was not involved in Frederikse’s study. Chambers also noted that the Intergovernmental Panel on Climate Change and others wouldn’t change their forecasts of the effects of climate change due to the findings.
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But the study nonetheless was a valuable advance in calculating the challenge that climate change poses. “That doesn’t seem like a lot,” Chambers, referring to the 0.005 inches per year, told Seeker. “But that is a substantial change in the seafloor. It does show the large forces at play here when you are moving water around because water is pretty heavy.”
Frederikse echoed those thoughts. He and his colleagues in his field refer to a “sea-level budget,” or an account of the rising and falling of the oceans that is analogous to tallying assets and liabilities on a balance sheet. In the same way accurate accounting is essential to running a business, knowing how the seas are rising is vital to figuring out how to deal with the problem.
“It gives us more confidence that because we understand the past, we can forecast the future better,” said Frederikse. “We want to do this bookkeeping. If you go to a place like New York and we see sea levels rising, we want to know why.”